The present invention resides in a conveyorized transport apparatus having a rail system for transporting articles carried by a trolley between one location and another and, more particularly relates to a variable height workstation capable of delivering a trolley from a first location on a subsidiary loop rail to a second diverted location adjacent a workstation.
A conveyorized transport system used for transporting workpieces between a series of subsidiary loops located adjacent individual workstations is disclosed in U.S. Pat. No. 4,615,273 issued on Oct. 7, 1986 and commonly assigned with the assignee of the present invention. Systems of this type usually involve a series of workers situated at workstations on either side or on both sides of the main rail. Individual ones of the trolleys are optically scanned and then, according to a predetermined program employed by a master computer or controller, diverted toward a selected one of the workstations located along the main rail. Each operator or worker associated with a particular workstation is charged with a given function to perform on the workpiece carried by the diverted trolley when it arrives at the associated workstation. These workers may repeat the same work function several hundred times over the course of a workday in performance of that work function. The trolleys travelling on the main rail are diverted from the main rail system onto subsidiary loops and are usually stopped on these subsidiary loops by gates where work material carried by respective ones of the trolleys await performance of work a function by an operator situated at the workstation.
The problem associated with these gates is that often they are situated along the subsidiary loop rail such that a stopped trolley and the workpiece carried by it are suspended on a portion of the subsidiary loop at a considerable distance above and away from the operator. Consequently, the operator usually must reach across this distance from a position adjacent his or her workstation to attempt to grasp the workpiece carried by the involved trolley which has stopped at the gate. Such extended grasping movements tend to exhaust the operator during the course of the workday thus robbing him or her of valuable time and energy which otherwise could be applied toward the work function at hand. Thus, a clear need for an ergonomically efficient workstation is apparent in order to situate workpieces adjacent a perspective worker so as to minimize the total number of movements required of the worker or operator in performance of a particular work function and thereby maximizing efficiency of productivity.
Other devices have been developed which address this problem. One such type of device is disclosed in the aforesaid U.S. Pat. No. 4,840,123. In this patent, a rail of a subsidiary loop is positioned adjacent a workstation and is capable of pivotal movement through two orthogonally oriented planes so as to position a trolley, carried at the free swinging end of the rail segment, adjacent a workstation. While such a device has been successful in increasing the ergonomic capability of the worker at a given workstation, it is however sometimes desirable to deliver a trolley carrying a workpiece to a workstation without having to swing a rail segment through any angular movement. Also, it has been found that significant mechanical means are needed to effect pivotal movement of the arm in this patent requiring both a complex control system and a variety of multifaceted moving parts.
Accordingly, it is an object of the present invention to provide a workstation capable of delivering trolleys from a subsidiary loop conveyorized transport apparatus to a workstation such that an operator performing a work function on a workpiece carried by a diverted trolley traveling on the subsidiary loop rail accomplishes this task with maximum ergonomic ease for a given individual.
Still a further object of the present invention is to provide a workstation scheme capable of efficiently managing the transportation of diverted trolleys from the main rail to a workstation by way of a subsidiary loop and back onto the main rail with a minimal amount of lag time by collecting the diverted trolleys at points along the subsidiary loop closest to the next destination to which they are to be advanced.